Together with the recent advancement of broadband technology, there has been an increasing demand for large-capacity, high-speed wireless communication. With the aim of increasing capacity, third-generation amplifiers have become widely used, and fourth-generation amplifiers are expected to make a progress. New communication systems such as the LTE (i.e., Long Term Evolution) have been put into practice, which will also serve to advance the trend toward increased capacity. Because of this, increases in output power and efficiency, size reduction, and cost reduction are required. A radar receiver module is expected to have an increased output power and a widened frequency band. Further reduction in operating costs and an increased efficiency for the size reduction of a cooling device are also required. In a phased array radar, radar modules inclusive of amplifiers may need to be arranged in an array form within a limited space. In consideration of this, further size reduction in the radar module is expected.
A conventional transceiver module has a configuration in which semiconductor devices such as amplifiers accommodated in packages are mounted in a metal case. Such a transceiver module tend to become voluminous. Efforts have been made to develop high-frequency packages utilizing an HTCC (i.e., high temperature co-fired ceramics) substrate or a LTCC (i.e., low temperature co-fired ceramics) substrate. Literatures also disclose high-frequency modules in which semiconductor-device electronic components such as amplifiers and filters are mounted on a dielectric multilayer substrate as described above.
Due to a demand for size reduction in high-frequency modules, it is preferable to stack semiconductor-device electronic components in a three dimensional structure. In such a case, however, it is difficult to secure low-loss, wideband performance because a contact failure easily occurs in high frequency.    [Patent Document 1] Japanese Laid-open Patent Publication No. 2011-171576    [Patent Document 2] Japanese Laid-open Patent Publication No. 2003-318319